1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device.
2. Description of the Related Art
In order to manufacture a group III nitride compound semiconductor device, conventionally, the utilization of a metal nitride layer as an undercoat layer has been proposed to obtain a group III nitride compound semiconductor layer having an excellent crystal.
Since the metal nitride layer has a conductivity, it can be used as an electrode.
In an undercoat layer formed of the metal nitride, a low temperature grown (a growth temperature: 400° C.) buffer layer (an AlN layer) is provided between the undercoat layer and a group III nitride compound semiconductor layer in order to maintain the excellent crystallinity of the group III nitride compound semiconductor layer to be grown thereon.
For the foregoing, see JP-A-2002-43617, JP-A-2000-77712 and JP-A-2000-114597.
It is preferable that the laminating structure of a semiconductor layer in a semiconductor device should be as simple as possible. A manufacturing process can be simplified and the yield of a semiconductor device can be enhanced, and a manufacturing cost can be reduced. Consequently, an inexpensive semiconductor device can be provided.
Moreover, the buffer layer has an insulating property depending on a material thereof. For this reason, a so-called conductivity in a vertical direction cannot be taken in the semiconductor device. In order to form an electrode, therefore, it is necessary to carry out etching for the semiconductor device. Also in this respect, the presence of the buffer layer can be a factor in an increase in the manufacturing cost of the semiconductor device.